We propose to apply the techniques of nuclear magnetic resonance spectroscopy using 1H, 13C, 15N, 19F, 31P, and 205Tl as probe nuclei. The biological systems to be studied include: enzymatic catalysis by serine proteases, and dehydrogenases, the acetylcholine receptor in the neuromuscular junction, cation flow in axonal conduction andoxytocin and vasopressin interaction with neurophysin.